The present invention relates to the installation of the upper skive plate in the fuser section of a electrophotographic copier/printer apparatus and in one of its aspects relates to an upper skive plate and to an assembly for removing and replacing the upper skive plate in the fuser section of an electrophotographic machine wherein the assembly prevents the blades on the skive plate from cutting or digging into the pressure roller of the fuser section while the upper skive plate is being installed and/or removed.
In a typical electrophotographic machine (e.g. copier, duplicators, printers, etc.), a continuous loop of photoconductor film is commonly used to transfer an image from an input section onto a receiving medium (e.g. a sheet of paper). The film is initially charged and then passes through an input section where an image (i.e. analog or digital) is projected onto the charged film. The film then moves through a developing section where a toner is applied to the charged image, and on through an image transfer section where the image is transferred to the sheet of paper or other medium. The paper is subsequently passed through a fuser section where the toner forming the image is fixed to the paper by elevated temperature and pressure. This is typically accomplished by passing the paper between two, opposed rollers in the fuser section, i.e. a pressure roller and a fuser roller, one of which is heated.
In fuser sections such as described above, the nip between the pressure and fuser rollers is extremely tight. To ensure that the paper will continue on through this nip and not stick to one or the other of the rollers, xe2x80x9cskive platesxe2x80x9d (i.e. upper and lower skive plates) are normally provided to strip the paper off the rollers (i.e. fuser and pressure rollers, respectively) after the toner is fused onto the paper. Each plate carries a plurality of thin, extremely sharp xe2x80x9cskivesxe2x80x9d (i.e. blades) (e.g. 0.004 inches thick) which effectively ride on its respective roller. These plates are rigidly mounted near the rollers at a precise location and angle to provide the proper stripping force without digging or gouging into the roller. As will be appreciated in this art, during assembly and service of the electrophotographic machine, the skive plates are frequently removed and then reinstalled. During this operation, the skive plates must be carefully handled so that the sharp skives do not gouge the respective rollers.
In known, prior art machines of this type, the installation of these skive plates presents a number of problems for a service technician, since there is usually nothing in the fuser section which prevents the skives from touching and possibly damaging the rollers if a technician mishandles the skive plate during a service operation. For example, in prior art fuser sections, the upper skive plate, to which the present invention is directed, must be carefully manipulated and then held in the proper position by a single service technician until he can secure the upper plate with screws or the like. While a competent technician can be trained to carry out the required, precise procedures, they still require the use of special tools and more importantly, involve the risk of human error which can lead to severe damage to the pressure roller.
Accordingly, those skilled in this art will recognize the need of simplifying the installation of the upper skive plate in the fuser section of an electrophotographic machine and making such installation effectively xe2x80x9cfool-proofxe2x80x9d to prevent the accidental gouging of the pressure and fuser rollers during the installation. Further, it is highly beneficial if the servicing of the upper skive plate can be carried out by a single technician without the need of special tools.
The present invention provides a fuser section for an electrophotographic apparatus which includes an upper skive plate which, in turn, can be easily and quickly installed in and removed from within the fuser section without the risk of accidentally damaging the pressure roller and the method for installing the skive plate in the fuser section. The upper skive plate carries a plurality of skives (i.e. sharp blade-like elements) thereon which are designed to ride on the pressure roller which, in turn, is rotatably mounted between two pivoted, load arms in the fuser section and strip sheets of paper off the pressure roller as the paper passes thereover.
Basically, the upper skive plate of the present invention is comprised of a plate having a front, rear, top, bottom, and two ends. A plurality of skives (i.e. sharp blade-like members) are mounted on and spaced across said bottom of said base plate so that the skives will ride on said pressure roller when said upper skive plate is in its operable position within the load arms of the fuser section. The skive plate has guide openings which cooperate with locator pins on the load arms to guide the plate to its operable position. The plate has at least one releasable latch thereon which releasably latches the plate in place once the plate has been properly positioned.
More specifically, the upper skive plate has a pair of releasable latches, one on each end of the plate. Each of these latches has a locking pawl which is affixed to one end of a shaft which, in turn, extends through the plate. A handle is fixed on the other end of the shaft and can move longitudinally with respect to the shaft but can not rotate with respect thereto. A spring, e.g. Belleville washer, is positioned between the handle and the shaft, the compression of which provides the clamping force necessary to latch the plate in place.
A guide assembly is affixed to each of the load arms and is comprised of a vertical guide element and a lateral guide element, the latter having a back surface thereon. A tapered, locator pin extends from the front of the back surface and is adapted to cooperate with guide openings in the upper skive plate to guide the plate to its operable position between the load arms. Once the plate is moved along the locator pins and against the front of the back surface, the latches are rotated to move the locking pawls in behind a respective clamping surface which, in turn, is on the rear of the back surface. As the pawls are moved onto the clamping surfaces, they will compress their respective springs thereby providing the force necessary to securely latch the upper skive plate in its operable position. To remove the upper skive plate, the procedure is merely reversed.